Electric heating element



C. R. .WASSELL.

ELECTRIC HEATING ELEMENT.

APPLICATION FILED MAY 5. 1916.

1,344,282. PatentedJune22,1920.

2 SHEETSSHEET 1.

flZzfford 1? WaZJ eZZ c. R. WASSE LL. ELECTRIC HEATING'ELEMENT.

,APPLlCATION FILED MAY 5, 1916.-

1 ,314:,282. Patented J 11116 22, 1920.

2 SHEETS-SHEET Z- 3 A 4, Mk Q UNITED STATES PATENT OFFICE.

CLIFFORD It. WASSELL, OF CHICAGO, ILLINOIS, ASSIGNOR TO CONLON ELECTRIC WASHER COMPANY, INC., OF CHICAGO, ILLINOIS, A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented June 22, 1920.

Application filed --'May 5, 1916. Serial No. 95,544.

To all whom it may concern:

Be it known that I, CLIFFORD R. IVAssELL, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Electric-Heating Elements, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawin s, forming a part of this specification.

lily invention relates to electric heating devices and its object is to provide a heating element which will be of greater efiiciency and of more simple and inexpensive structure than those of the prior art.

According to my invention, I provide a supporting or carrying member of refractory insulating material, such as fire clay, and I provide in the face of this member a groove, preferably in spiral form, or two parallel grooves in such form, upon the inside of eachside of which a supporting shoulder is formed. These shoulders preferably lie in substantially a single plane and the resistance wire, of such material as nichrome or chromel, is prepared in undulated form in substantially a single plane and is laid upon these shoulders, only the edges of the undulated heating element being thus in contact with the carrier.

Thus I produce a definite plane of radiation and the very small contact between the heating element and the carrier reduces loss of heat by conduction to a minimum. The space between the under side of the heating unit and the body of the carrier, which results from this arrangement and structure reduces loss of heat by radiation and ac cordingly the total efficiency of the device is ver greatly increased.

he arrangementwhich I provide lends itself readily to the use of two resistance units which may be variously connected with the source of current, one alone for medium heat, both in series for low heat, or both in multiple for high heat, all of which will be clear by reference to the accompanying drawings, in which- Figure 1 is a plan view of my heating device;

Fig 2 is an under side view thereof; Fig. 3 is a plan view thereof with the top plate removed;

Fig. 4 is a sectional view taken on the plane of the line 4--1 of Fig. 1 in looking in the direction indicated by the arrows; and

Fig. 5 is a partial sectional view, similar to Fig. 4, drawn on a larger scale.

The base 6, of some suitable refractory electrical insulating material, such as fire clay, has mounted thereon a supporting ring 7, secured in place by means of screws 8-8 passing through the feet 9-9. Secured in any suitable manner within the ring 7 is the secondary supporting member 10, to the top of which the heating element carrying member 11 is secured by means of screws 12-12. The carrying member 11 is of some refractory electrlcal insulating material, such as fire clay, and the top thereof is provided with a pair of spiral grooves 131 3 in parallel relation to each other, consumingpractically the entire areaof the top face of the member. These grooves are of uniform cross section, and of the formation illustrated in the cross sectional views, Figs. 4 and 5. It will be seen that each of the grooves is provided upon each side of the interior thereof with a shoulder 14, the grooves being formed considerably deeper than the plane of the shoulders i k-14 to provide the auxiliarydepression 15.

A heating element is disposed in each of these grooves and each heating element comprises an undulated resistance wire 16, of some such material as nichrome or chromel, the undulations being disposed in a single plane and the resistance element as a whole being spirally arranged so as to con-' form to the formation of the groove. As illustrated, the resistance element 16 is laid in the groove, resting upon the shoulders 14-44, which are also disposed in a single plane. It will be noted that only the ends of the undulations, or what may be termed the edges of the resistance element as a whole, are in contact with the carrying member 11, this being made possible by the shoulder, formation. In this way I produce a definite plane of radiation wherein the heating element is distributed uniforml over a considerable area. The very smal contact between the heating element and the carrier reduces loss of heat by conduction to minimum. The space below the heating element, provided by the portion 15, is

Lie-i structure one? 01' importance, since, by th's by radiation is arrangement, loss of heat reduced to a minimum.

As will be seen from Fig. .2, the inner ends of the two heating elements are connected together by a jumper Wire 17, this jumper Wire, by means of a conductor 18, being connected With a. terminal member 19. The free end of one of the heating elements is connected by metres of s conductor 20 With the terminal member 21 end the free end of the other heating element is con nected, by means of conductors 22 and 23, with the terminal. nieniibers and 25, re spectivel The tour terminal members grouped together for cooperzition With separable connector and, by choosing the proper terminal member, the two elements may be connected in circuit in series, or in multiple, one of the elements may be con nected in circuit alone.

A cover plate 26 is disposed over the member 11 v l element, this cover 'ite being provi with two e the course u. q W p q o 4/ 6 Moll WED b the s carrying .neinher i sheet of in-.. suletir, cs d between the under or the the top of the csrryh nienber ll, this sheet of in" suloting rial being perforated similarly to the plate 26 having its perforations registering with those in the plate, so that, as illustrated in l, the heating elements are precticslly entirely exposed for eh ective action upon Whatever is set upon the plate 26 to be heated. The sheet of insulating materiel 28 be et mice and is also practicable at this der sic or l on electric heating device, it incinoer of rerrsctory insulating material, said i'neniber llfifl. e groove therein, opposing shoulders in said groove and o rlut heating elemen heving its edges resting upon and thus supported by said shoulders. A

2. In an electric heating device, u incur her or": refractory insulating material, suid member having a spiral groove therein, opposing shoulders in said groove, and u flat unduluted heating element having its edges resting uponv thus supported. by

said shoulders.

said member having sunken fist ing its 1 q -v 1 1 1: 1r\ wi l ya bl) and CblCl ,2. e S c( 31al( ,tc suit nccm er over said groove, said cover piste having at series or holes therein'following said 5. in an electric hosting device, :1 member of refractory insulating materiel, said menuber huving u groove therein, opposing shoulders in said groove, u fiat heating element having its edges resting upon and thus supported by suid shoulders and :1 cover plate secured to said member ov r said roove, there insulating material be tween said cover plate and suid element.

l an electric heuting device, at nieinrefractory insulating material, said her 0 member having it groove therein, opposing shoulders in said groove, e heuting element having its edges resting upon said shoulders and a cover plate secured to suid r ember over said groove, there bein insulating material between said cover plate and suid element, said cover plate and. said insulatnisteriul having 21 series of holes therein following said groove.

T. in an electric heating device, u base of refractory insulating muteriul, s groove in topped shoulders, at f heuting element in the groove supported on suid shoulders and held laterally by the Walls of the groove, :1 cover plute secured to said member, sold cover plate having it series of holes therethrough following said heating element.

,8. ln electric heating device of the character described, at inernber oil refractory insulating material, seid member having at groove therein for receiving at heating element, lilut shoulders in the groove, Wells above the shoulders being verticul and parallel, and u lot heatin element Within said groove resting on and supported by suid shoulders and held laterally by the Walls of the groove.

In Witness Whereoi ll hereunto subscribe my name this 29th day of April, A. D. 1916.

onrrronn n. WASSELL. 

